Redesign effect ID system: fix semantic mismatch between '-' (No effect) and its visual representation

[tnkshuuhei]

Background

In the current effect ID system (OUTCOME_EFFECTS), "-" means "No effect," but its visual representation (Minus icon + red color) intuitively suggests "Negative effect," creating a semantic mismatch.

In research contexts, negative effects (e.g., negative regression coefficients) are a valid concept, so the ID system needs a fundamental redesign.

Current State

Meaning	ID	Icon	Color
Unclear	N/A	HelpCircle	Gray
Positive	+	Plus	Green
No effect	-	Minus	Red ← Mismatch
Mixed	+-	Blend	Gray
Side effects	!	AlertTriangle	Orange

Problems

• "-" + red + Minus icon intuitively means "negative effect," but actually represents "no effect" (neutral)
• "Negative effect" category does not exist in the system

Proposal

Meaning	Current ID	New ID	Icon	Color
Unclear	N/A	? or N/A	HelpCircle	Gray
Positive	+	+	Plus	Green
Negative	(none)	-	Minus	Red
No effect	-	0	Circle	Gray
Mixed	+-	+-	Blend	Gray
Side effects	!	!	AlertTriangle	Orange

Scope of Impact

beaconlabs-io/evidence repository (upstream)

• Update OUTCOME_EFFECTS constant and OutcomeEffect type
• Update Zod schema (EvidenceSchema) outcome field
• Rewrite existing evidence MDX files: outcome: "-" → outcome: "0"
• Republish npm package

beaconlabs-io/muse repository (this repo)

• components/effect-icons.tsx — Update effectData IDs, icons, and colors
• app/[lang]/effects/page.tsx — Update effectTranslationKeys
• messages/en.json, messages/ja.json — Add/update translation keys
• components/effect-filter.tsx — Filter UI
• app/[lang]/search/page.tsx — URL parameter handling
• lib/evidence-filters.ts — Filter logic
• Display components (evidence-card, EvidenceResults, table-column, etc.)

Notes

• Check compatibility with data already attested on-chain (EAS)
• Consider backward compatibility for URL parameters like ?effects=-